A liquid crystal display (LCD) is a type of flat panel display (FPD) which displays images by the properties of the liquid crystal material. In comparison with other display devices, the LCD has the advantages of being lightweight, compact, having a low driving voltage, and having low power consumption and thus has already become the mainstream product in the consumer market. In the traditional manufacturing process of an LCD panel, it comprises a front-end array process, a mid-end cell process, and a back-end modulation process. The front-end array process is used to produce thin-film transistor (TFT) substrates (also called array substrates) and color filter (CF) substrates; the mid-end cell process is used to combine the TFT substrate with the CF substrate, then fill liquid crystal into a space therebetween, and then they are cut to form panels compatible with a suitable product size; and the back-end modulation process is used to execute an installation process on the combined panel, a backlight module, a panel driver circuit, an outer frame, etc.
As mentioned above, LCD driver chips are important components of the LCD, and the main function thereof is to output the needed voltage to pixels, so as to control the twist degree of the liquid crystal molecules. There are two types of LCD driver chips: one is the source driver chip arranged on the X-axis, the other is the gate driver chip arranged on the Y-axis. In other words, the source driver chips control image signals, and the gate driver chips control gate switch signals, so they have different functions for the LCD panel. Simply speaking, images of an LCD are formed by scanning lines one by one. The gate driver chip controls the vertical signals. If the scanning is started from the topmost line, the first pin of the gate driver chip is set to be switched on, and the others are set to be switched off. The signals in the source driver chip are the real signal (horizontal), and the sent signal is only accepted by the horizontal pixels of the first line. After the signal of the first line is transmitted, the second line will be the next one, while the content of the source driver chip is changed to the second line, and the second pin of the gate driver chip is switched on, and the others are switched off, so that the data is transmitted to the second line.
Furthermore, the assembly of the driver chips of the back-end modulation process is an assembling technology which combines the packaged source driver chips and the packaged gate driver chip with the LCD panel. There are various packaging types of the driver chip for an LCD, such as quad flat package (QFP), chip on glass (COG), tape automated bonding (TAB), chip on film (COF), etc. The COF structure has flexibility and smaller circuit pitches, so has become the mainstream technology of the package of driver chips.
Usually, a tape-packaged COF is processed by rolling and delivering in whole the tape, and in the traditional manufacture of an LCD panel, it is necessary to provide the above-mentioned COFs bonded to two edges thereof. Referring now to FIGS. 1A, 1B and 2, a top view of a traditional source COF tape is illustrated in FIG. 1A; a top view of a traditional gate COF tape is illustrated in FIG. 1B; and FIG. 2 is a schematic top view showing that the traditional source and gate COFs are bonded on a liquid crystal panel. Specially explaining, for conveniently describing, the above-mentioned figures are shown in simplification, wherein the number of traces is simplified, and some details which are unrelated to the explanation are also omitted.
As shown in FIG. 1A, a source COF tape 80 mainly comprises a base tape 80a and a plurality of source COFs 81, wherein the source COFs 81 are arranged on the base tape 80a, and by a plurality of punching processes the needed source COFs 81 can be cut from the base tape 80a of the source COF tape 80.
As shown in FIG. 1B, a gate COF tape 90 mainly comprises a base tape 90a and a plurality of gate COFs 91, wherein the gate COFs 91 are arranged on the base tape 90a, and by a plurality of punching processes the needed gate COFs 91 can be cut from the base tape 90a of the gate COF tape 90.
Moreover, as shown in FIG. 2, a liquid crystal panel 100 has a first side edge 110 and a second side edge 120 which are perpendicular to each other. By a plurality of processes of thermo-compression bonding the source COFs 81 can be bonded to the first side edge 110 of the liquid crystal panel 100, and the gate COFs 91 can be bonded to the second side edge 120 of the liquid crystal panel 100, so as to accomplish the assembly operation of the driver chips of the liquid crystal panel 100.
As described above, because the trend in developing LCD panels tends towards increasing the size of the panels, and the request for productivity is higher and higher, bonding two edges of an LCD at the same time has become a newly developing trend. However, it is necessary to provide both the above-mentioned source COFs 81 and the gate COFs 91. If the two different types of COF need to be provided simultaneously, it is necessary to prepare two sets of independent operating equipment, thus increasing the cost of the equipment.
As a result, it is necessary to provide a COF tape and a corresponding COF bonding method to solve the problems existing in the conventional technology.